Contamination of groundwater and soil with various types of organochlorine compounds including tetrachloroethylene (PCE) and trichloroethylene (TCE) has been a serious issue around the globe. This issue often has been covered thoroughly by mass media such as newspapers and the like, leading to a strong social demand for development of technologies for remedying environments contaminated with these substances.
Such technologies for remedying a contaminated environment include a physicochemical method and a biological method. Among these methods, particularly suited for remediation with respect to low-level contamination is the biological method of remedying an environment using a microorganism (bioremediation). Bioremediation is widely expected to be put to practical use since it can be performed at low cost without requiring soil excavation, allows even an environment under a building to be remedied easily, and achieves a reduction in environmental burdens.
Bioremediation is performed in the following manners. That is, for example, various nutritive substances or the like are supplied to microorganisms originally inhabiting contaminated soil or groundwater so that the capability of the microorganisms to degrade and eliminate environmental contaminants is enhanced (biostimulation). Alternatively, microorganisms having the capability to degrade and eliminate environmental contaminants are introduced directly into a contaminated environment (bioaugmentation: JP 2003-154332 A, for example). An example also is known in which biostimulation and bioaugmentation were used to remedy an environment that was groundwater contaminated with TCE, yielding excellent results.
In implementing bioremediation, it is judged whether a contaminated site can be treated with biostimulation or should be treated with bioaugmentation in which microorganisms having the capability to degrade contaminants are introduced from outside of a system, and it has been desired that such judgment be performed promptly (JP 2000-079000 A, for example).